(a) Field of the Invention
This invention relates to a novel three-step process for the preparation of 3,3-aryl- and/or heteryl-disubstituted phthalides useful in the art of carbonless duplicating as, for example, in pressure-sensitive systems and in thermal marking systems; and to novel 3-aryl- or heteryl-substituted phthalides and 2-(.alpha.,.alpha.-aryl- and/or heteryl-disubstituted)methyl benzoic acid intermediates produced by said process.
(b) Description of the Prior Art
Several classes of organic compounds of widely diverse structural types are known to be useful as colorless precursors for carbonless duplicating systems. Among the more important classes, there may be named phenothiazines, for example, benzoyl leuco methylene blue; phthalides with which this invention is concerned, for example, crystal violet lactone; fluorans, for example, 2'-anilino-6'-diethylaminofluoran and 2'-dibenzylamino-6'-diethylaminofluoran; and various other types of colorless precursors currently employed in commercially accepted carbonless copy systems. Typical of the many such systems taught in the prior art are those described in U.S. Pat. Nos. 2,712,507, 2,800,457 and 3,041,289 which issued July 5, 1955, July 23, 1957 and June 26, 1962, respectively.
The following items to date appear to constitute the most relevant prior art with regard to the instant invention. Rodionov and Fedorova in the Bulletin de 1'Academie des Sciences de 1'URSS Classes des Sciences Chemie 81-8 (1940) [Chemical Abstracts 35: 2488.sup.4 (1941)] describe the preparation of 3-aryl-substituted phthalides, for example, 3-(4-dimethylaminophenyl)phthalide, 3-(4-diethylaminophenyl)-6,7-dimethoxyphthalide and 3-(4-ethylmethylaminophenyl)-6,7-dimethoxy phthalide, by heating the appropriate N,N-dialkylaniline with the appropriate phthalaldehydic acid. The physical characteristics of the compounds are described without giving any indication as to their utility. Noland and Johnson in the Journal of the American Chemical Society 82, 5143-5147 (1960) describe the preparation of 3-heteryl-substituted phthalides, for example, 3-(1,2-dimethyl-3-indolyl)phthalide, 3-(2-methyl-3-indolyl)-6,7-dimethoxy phthalide and other isomers by fusing equimolar proportions of an indole and a phthalaldehydic acid. Physical data are given for the compounds and there is no indication of their utility. Rees and Sabet in the Journal of the Chemical Society, 680-687 (1965) describe the preparation and physical characteristics of 3-(3-indolyl)phthalide. There is no indication of the utility of the compound in the reference which is prepared by the acid-catalyzed interaction of indole and phthalaldehydic acid. In the same reference, Rees and Sabet describe the preparation and physical characteristics of .alpha.,.alpha.-di-(3-indolyl)-2-methylbenzoic acid prepared by the interaction of 3-(3-indolyl)phthalide with indole in refluxing alcoholic potassium hydroxide. No utility of the compounds is given in the reference.
U.S. Pat. Nos. 2,742,483 and 3,185,709, which issued Apr. 17, 1956 and May 25, 1965 respectively, disclose 2-[4,4'-bis-(dimethylamino)benzhydryl]-5-dimethylaminobenzoic acid which is obtained from the interaction of m-dimethylaminobenzoic acid and 4,4'-bis(dimethylamino)benzhydrol. The compound is described as the intermediate to 3,3-bis(4-dimethylaminophenyl)-6-dimethylaminophthalide which according to the earlier patent, is obtained by permanganate oxidation and according to the later patent, by oxidation with molecular oxygen. The 3,3-bis(4-dimethylaminophenyl)-6-dimethylaminophthalide (crystal violet lactone) is well known as a colorless precursor for carbonless duplicating systems.
Belgian Pat. No. 808,535, granted Dec. 12, 1973, discloses 3-[2,4-bis(dimethylamino)phenyl]-3-(4-dimethylaminophenyl)-6-dimethylamino phthalide and similar compounds which are prepared by condensing the appropriate o-(4-dialkylaminobenzoyl)benzoic acid with the appropriate N,N,N',N'-tetraalkyl-m-phenylenediamine. These compounds are described as being useful as colorless precursors for carbonless duplicating systems.
U.S. Pat. No. 3,491,112, which issued Jan. 20, 1970, discloses 3-(4-dimethylaminophenyl)-3-(1,2-dimethyl-3-indolyl)-6-dimethylaminophthal ide which is prepared by condensing 4,4'-bis(dimethylamino)benzophenone-2-carboxylic acid and 1,2-dimethylindole. The compound has utility as a colorless precursor for carbonless duplicating systems.
U.S. Pat. No. 3,829,322, which issued Aug. 13, 1974, discloses 3-(2-methyl-4-N-ethylbenzylaminophenyl)-3-(1-ethyl-2-methyl-3-indolyl)-6-d imethylaminophthalide which is prepared by interacting 1-ethyl-2-methyl-3-(4'-dimethylamino-2'-carboxybenzoyl)-indole and N-benzyl-N-ethyl-3-methylaniline. The compound has utility as a colorless precursor for carbonless duplicating systems.
(c) Prior Publication
Japanese Patent Publication No. Sho 50-124930, which was published on Oct. 1, 1975, describes a series of compounds having the formula ##STR1## wherein each of R.sub.1 and R.sub.2 represents a hydrogen atom, a lower alkyl, haloalkyl, alkoxyalkyl, acyloxyalkyl, cyanoethyl, allyl, propargyl, cyclohexyl, benzyl or phenyl in which the benzene ring may be substituted by lower alkyl, halogen, nitro or lower alkoxyl radical, or R.sub.1 and R.sub.2 together may form a heterocyclic ring with the adjacent nitrogen atom; R.sub.3 represents a hydrogen atom or chlorine atom; R.sub.4 represents a benzene ring or heterocyclic ring which may be substituted. According to the reference, the compounds are prepared by the condensation of an appropriate aromatic aldehyde and an appropriate benzoic acid at an elevated temperature in the presence of a dehydrating agent and are described as colorless precursors in carbonless, pressure-sensitive and thermal copy systems. This reference appeared subsequent to applicant's invention described herein and less than one year prior to the filing date of this application.